Continuous functions on path connected and connected sets, Real Analysis II

Опубликовано: 09 Октябрь 2024
на канале: Dr. Bevin Maultsby
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In this video, we prove two results that show how certain topological properties are preserved under continuous functions. (Review connectedness and path-connected here:    • Connected and Path Connected Sets, Re...  .)

First, we prove that if a continuous function f has a path-connected domain, then its image f(A) is also path-connected. We start by selecting two points in the image, trace them back to the domain, and use the fact that the domain is path-connected to construct a continuous path between them. Applying the function f to this path results in a continuous path in the image, proving that f(A) is path-connected.

Next, we prove that if f is continuous and the domain A is connected, then the image f(A) is connected. This proof takes a different approach using contrapositive. We assume that f(A) can be separated into two disjoint open sets and show that this would imply the domain A can also be separated, which contradicts the assumption that A is connected. Therefore, f(A) must be connected.

These results highlight that properties like compactness, path-connectedness, and connectedness are preserved under continuous functions, while other properties, such as being open or closed, are not necessarily preserved. Note here these results are proved in a general metric space setting.

#Mathematics #Topology #PathConnected #ConnectedSets #ContinuousFunctions #MathProof #RealAnalysis #STEM #Compactness #Connectedness #math #advancedcalculus


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